Sizing an inverter
An inverter’s continuous rating has to cover the watts that are on together, not the daily watt-hours. The Megawatt battery calculator already estimates that continuous peak from the appliances you check. A luxury coach with the AV package checked, and the air conditioner left off, is 2,300 watts in that table. Checking multi-zone air conditioning jumps the peak by another 4,500 watts.
The solar planner multiplies that peak by 1.25 and then picks the next bin in a list from 1,000 to 6,000 watts. The 1.25 is a planning margin used on this site. It is not printed in the old calculator, and it is not a claim about the National Electrical Code. Change it if your installer uses a different margin.
Surge is the part this number misses. A roof air conditioner can draw several times its running watts for a moment. The old calculator does not publish a surge column, so this site does not invent one. Read the inverter’s surge spec and the air conditioner’s locked-rotor or start data from the appliance manual.
The same peak watts choose battery voltage in the original widget. Over 3,000 continuous watts it leaves 12 volts. Over 5,000 it leaves 24 volts. That is why a residential refrigerator plus air conditioning pushes the plan toward a higher-voltage bank and a larger inverter. Megawatt’s affiliate list has the batteries and the solar packs. It does not have an inverter ASIN, so this page will not pretend one of the battery links is an inverter.
The original solar calculator’s footer still applies: talk to a certified electrician before you modify the electrical system.